In vitro reduction of colistin susceptibility and comparative genomics reveals multiple differences between MCR-positive and MCR-negative colistin-resistant Escherichia coli
In vitro reduction of colistin susceptibility and comparative genomics reveals multiple differences between MCR-positive and MCR-negative colistin-resistant Escherichia coli
复制标题
粘菌素敏感性的体外降低和比较基因组学揭示了 MCR 阳性和 MCR 阴性粘菌素耐药大肠杆菌之间的多重差异
DOI：
10.2147/idr.s210245
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发表时间：
2019-01-01
影响因子：
3.9
通讯作者：
Li, Lanjuan
中科院分区：
文献类型：
--
作者：
Luo, Qixia;Niu, Tianshui;Li, Lanjuan
目的：尽管临床上越来越多地报道了对粘菌素的耐药性，但导致大肠杆菌对粘菌素耐药性的遗传机制尚未得到充分表征。在此，我们评估了动员型黏菌素耐药（MCR）阴性和MCR阳性大肠杆菌临床分离株中黏菌素耐药性的演变。方法：使用逐步降低粘菌素敏感性来进化自发突变的粘菌素抗性后代。通过最低抑菌浓度（MIC）测定确定耐药表型，并使用PCR和逆转录-定量PCR研究可能的耐药机制。通过全基因组测序和比较基因组学鉴定实验室进化的突变体的突变基因。还将突变体的适应性成本和血清抗性与相应的野生型进行了比较。结果：暴露于粘菌素后，MCR阴性分离株的MIC增幅高于MCR阳性分离株。pmrAB和相关基因的上调在MCR阴性分离株中明显，但在MCR阳性分离株中不明显。突变体和它们相应的野生型（WT）的比较基因组分析显示，在编码膜转运蛋白和双组分系统的基因中存在许多突变。此外，与相应的WT相比，MCR阴性突变体表现出比MCR阳性突变体更高的适应性成本，但表现出相似的血清抗性。结论：我们的研究结果揭示了多方面的差异，MCR阳性和阴性E。结果表明，该方法可为临床用药提供参考值。
Objectives: Although resistance to colistin is increasingly reported from clinical settings, the genetic mechanisms that lead to colistin resistance in Escherichia coli have not been fully characterized. Here, we assess the evolution of colistin resistance in clinical isolates of mobilized colistin resistance (MCR)-negative and MCR-positive Escherichia coli. Methods: Spontaneously mutated colistin-resistant progeny were evolved using a step-wise reduction of colistin susceptibility. Resistance phenotypes were confirmed by minimum inhibitory concentration (MIC) determination, and the probable resistance mechanisms were investigated using PCR and reverse transcription-quantitative PCR. Mutated genes of the laboratory-evolved mutants were identified by whole-genome sequencing and comparative genomics. Fitness costs and serum resistance of the mutants were also compared to the corresponding wild types. Results: MCR-negative isolates displayed higher increases in MICs than did MCR-positive isolates following colistin exposure. Upregulation of pmrAB and associated genes was evident among MCR-negative isolates but not MCR-positive isolates. Comparative genomic analysis of mutants and their corresponding wild-types (WTs) revealed numerous mutations in genes encoding membrane transporters and two-component systems. Additionally, MCR-negative mutants exhibited higher fitness costs than MCR-positive mutants compared with their corresponding WTs but displayed similar serum resistance. Conclusion: Our findings reveal multiple differences between MCR-positive and MCR-negative E. coli strains following colistin exposure, which provide reference values for clinical medication.